一、核心配置文件
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
3 "http://mybatis.org/dtd/mybatis-3-config.dtd">
4 <configuration>
5 <!-- 最开始加载引用db.properties文件 -->
6 <properties resource="db.properties"/>
7 <!-- 取别名 以下情况别名为类名 -->
8 <typeAliases>
9 <package name="com.myBatis.entity"/>
10 </typeAliases>
11 <!--
12 development : 开发模式
13 work : 工作模式
14 -->
15 <environments default="development">
16 <environment id="development">
17 <transactionManager type="JDBC" />
18 <!-- 配置数据库连接信息 -->
19 <dataSource type="POOLED">
20 <property name="driver" value="${driver}" />
21 <property name="url" value="${url}" />
22 <property name="username" value="${username}" />
23 <property name="password" value="${password}" />
24 </dataSource>
25 </environment>
26 </environments>
27 <!-- 引用映射文件 -->
28 <mappers >
29 <mapper resource="com/myBatis/mapper/classesMapper.xml"/>
30 </mappers>
31 </configuration>
二、实体类
2.1Teacher
1 package com.myBatis.entity;
2
3 public class Teacher {
4 // 定义实体类的属性，与teacher表中的字段对应
5 private int id; // id===>t_id
6 private String name; // name===>t_name
7 public int getId() {
8 return id;
9 }
10 public void setId(int id) {
11 this.id = id;
12 }
13 public String getName() {
14 return name;
15 }
16 public void setName(String name) {
17 this.name = name;
18 }
19 @Override
20 public String toString() {
21 return "Teacher [id=" + id + ", name=" + name + "]";
22 }
23
24
25 }
2.2Classes
1 package com.myBatis.entity;
2
3 public class Classes {
4 private int id; // id===>c_id
5 private String name; // name===>c_name
6 /**
7 * class表中有一个teacher_id字段，所以在Classes类中定义一个teacher属性，
8 * 用于维护teacher和class之间的一对一关系，通过这个teacher属性就可以知道这个班级是由哪个老师负责的
9 */
10 private Teacher teacher;
11 public int getId() {
12 return id;
13 }
14 public void setId(int id) {
15 this.id = id;
16 }
17 public String getName() {
18 return name;
19 }
20 public void setName(String name) {
21 this.name = name;
22 }
23 public Teacher getTeacher() {
24 return teacher;
25 }
26 public void setTeacher(Teacher teacher) {
27 this.teacher = teacher;
28 }
29 @Override
30 public String toString() {
31 return "Classes [id=" + id + ", name=" + name + ", teacher=" + teacher + "]";
32 }
33
34 }
三、映射文件
teacherMapper.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
3 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
4 <!--
5 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，
6 这样就能够保证namespace的值是唯一的
7 -->
8 <mapper namespace="com.myBatis.mapper.teacherMapper">
9 <!-- 根据id查询得到一个user对象 -->
10 <select id="getteacher" parameterType="int" resultType="Teacher">
11 select * from teacher where id=#{id}
12 </select>
13
14 </mapper>
15
classesMapper.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
3 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
4 <!--
5 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，
6 这样就能够保证namespace的值是唯一的
7 -->
8 <mapper namespace="com.myBatis.mapper.classesMapper">
9 <!-- 嵌套结果：使用嵌套结果映射来处理重复的联合结果的子集
10 封装联表查询的数据(去除重复的数据)
11 根据id查询得到一个user对象 -->
12 <select id="getclassess" parameterType="int" resultMap="ClassResultMap">
13 select * from classes c, teacher t where c.t_id=t.t_id and c.c_id=#{id}
14 </select>
15 <!-- 使用resultMap映射实体类和字段之间的一一对应关系 -->
16 <resultMap type="Classes" id="ClassResultMap">
17 <id property="id" column="c_id"/>
18 <result property="name" column="c_name"/>
19 <association property="teacher" javaType="Teacher">
20 <id property="id" column="t_id"/>
21 <result property="name" column="t_name"/>
22 </association>
23 </resultMap>
24
25 </mapper>
26
四、测试类
1 package myBatisTest;
2 import org.apache.ibatis.session.SqlSession;
3 import org.junit.Test;
4
5 import com.myBatis.entity.Classes;
6 import com.myBatis.util.myBtaisUtil;
7
8 public class TestUser {
9 /**
10 *
11 //修改
12 @Test
13 public void testUpdateUser() {
14 SqlSession sqlSession=myBtaisUtil.getsqlSession();
15 //先查找
16 String select = "com.myBatis.mapper.userMapper.xml.getUser";
17 EUser user = sqlSession.selectOne(select, 7);
18 System.out.println(user);
19 //再修改
20 user.setName("改啦7777");
21 user.setAge(50);
22 String update = "com.myBatis.mapper.userMapper.xml.updateUser";
23 int i = sqlSession.update(update, user);
24 System.out.println(i);
25 EUser user1= sqlSession.selectOne(select, 7);
26 System.out.println(user1);
27 }
28
29
30 //添加
31 @Test
32 public void testAddUser() {
33 SqlSession sqlSession=myBtaisUtil.getsqlSession();
34 String add = "com.myBatis.mapper.userMapper.xml.addUser";
35 EUser user = new EUser();
36 user.setName("用户孤傲苍狼");
37 user.setAge(20);
38 int i = sqlSession.insert(add, user);
39 System.out.println(i);
40 }
41 //删除
42 @Test
43 public void testDeleteUser() {
44 SqlSession sqlSession=myBtaisUtil.getsqlSession();
45 String delete = "com.myBatis.mapper.userMapper.xml.deleteUser";
46 int i= sqlSession.delete(delete, 6);
47 System.out.println(i);
48 }
49 */
50 //查询
51 @Test
52 public void testGetUser() {
53 SqlSession sqlSession=myBtaisUtil.getsqlSession();
54 String select = "com.myBatis.mapper.classesMapper.getclassess";
55 Classes classes = sqlSession.selectOne(select, 1);
56 System.out.println(classes);
57 }
58 }
时间： 2024-10-07 22:38:17